Scissors jacks are known in the art. In these jacks, ends of scissors arms are joined by a continuous lead screw. The lead screw is secured in a non-rotatable threaded sleeve secured to one scissors arm and passes freely through a non-rotatable body secured to the other scissors arm. At its other end (drive end), the lead screw is enlarged for example by a hex-nut united to its end, for being driven.
The scissors arms are jacked up and down (for elevating and lowering the body of the vehicle) by rotating the lead screw by driving the hex-nut.
For safety purposes, the jack must stay in its elevated position even if the enlarged end shears off or breaks off. Preferably that end shears off at predetermined input torque to ensure the safety of the jack.
It is therefore an object of the invention to provide an improved jack and constituents and components therefor.
It is a further object of the invention to provide a jack comprising a lead screw carrying an improved structure which may be caused to shear at a predetermined torque.
It is a further object of the invention to provide improved components which are easier to assemble and use to assemble the jack.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of embodiments thereof.